The present invention relates to contact bodies, such as gas/liquid contact bodies, comprised of two or more individual contact sheets, and to a method and apparatus for connecting two or more contact sheets. More particularly, the present invention relates to a method and apparatus for connecting two or more contact sheets with at least one positive lock between the contact sheets, and to the contact bodies so made.
Various types of apparatus and products are known in the art for providing gas/liquid contact for several different purposes. Among such purposes, for example, are heat transfer, such as evaporative heat exchangers, the removal of pollutants from a gas (gas scrubbing), use in trickle filters (a type of biological filter), artificial reefs, and other industrial or other types of uses. Gas/liquid contact bodies are generally designed to promote the intimate mixture of and heat exchange between two fluid streams. The fluid streams can be concurrent-flowing, cross-flowing, or counter-flowing streams. The intimate mixture of two fluid streams, air and water for example, or other gases and liquids, is accomplished by providing a series of corrugated contact sheets in contact with each other such that the crests and valleys of the corrugations form channels or passageways. The contact body can be positioned so that the channels are oriented in a vertical manner and the water is allowed to trickle down the walls of each channel while a gas, typically air, flows through the contact body simultaneously, thereby cooling the water. As mentioned above, the air can flow concurrently with the water, cross-currently (i.e., horizontally in the case of vertically disposed channels), or counter-currently. Air flow may be improved by the use of a blower or a fan.
Many variations to the design of contact sheets used to form the contact bodies have been described. For example, U.S. Pat. Nos. 4,668,443 and 5,217,788, the entire contents of which are herein incorporated by reference, describe various shapes and forms of contact sheets. Efforts have been directed to enhancing the wettability of the sheets, or increasing the surface area of the contact body, or reducing the impedance to air flow, while enhancing or at least maintaining the gas and liquid contact efficiency. Variations have been made in an effort to reduce the cost of such contact bodies, or to make construction easier.
At any rate, all contact bodies comprise a plurality of contact sheets in contact with, and preferably fastened to, one another in some manner. Most often an adhesive is used to fix one sheet to another at the intersecting points of contact. Heat-welding is another common technique used in connecting the sheets. However, a problem with conventional methods of connecting contact sheets is the lack of durability. Adhesives and spot welds can wear and deteriorate to a point where the strength of the connection is such that relatively slight forces can separate the sheets. Such a separation can be a serious problem to the structural integrity of a contact body. Other problems associated with adhesives and welding methods of connection are high cost, low speed and low productivity. The application of an adhesive at all points of contact between two adjacent contact sheets, and/or the fusing together of two sheets, is time consuming and uses a large amount of adhesive and/or energy.
Potential solutions to these problems have been proposed but have not adequately dealt with the problems. For example, U.S. Pat. No. 3,281,307, the entire contents of which are herein incorporated by reference, discloses the use of “cup-like” depressions and corresponding projections for the purpose of situating adjacent contact sheets. However, U.S. Pat. No. 3,281,307 does not disclose or suggest that any positive lock is provided by such projections and depressions. Further connecting means, such as heat sealing, adhesives, screws, bolts and preferably welding, are still required to join the adjacent sheets together. U.S. Pat. No. 5,413,872, the entire contents of which are herein incorporated by reference, describes the use of pressure fasteners. However, such a mechanism of connecting contact sheets may still be susceptible to inadvertent separation since the amount of force required to separate is equal to, or at least not significantly greater than, the force needed to join the pressure fasteners.
Thus, there exists a need in the art for a method of connecting contact sheets in which the resulting connection is strong, durable, economical and substantially inseparable. The present invention satisfies this need.